Excess voltage cutout for lowvoltage systems



Dec. 26, 1950 v, JORGENSEN 2,535,423

EXCESS VOLTAGE CUTOUT FOR LOW-VOLTAGE SYSTEMS Filed Jan. 11, 1946 III/III/I/I/II IN VENTOR ATTORNEY.

Patented Dec. 26, 1950 UNITED STATES PAT-ENT- EXCESS VOLTAGE CUTOUT FOR Low VOLTAGE SYSTEMS Karl Valdemar J rgensen, Kaerby, Aalbor'g,

Denmark 7 Application January 11, 1946, Serial No. 640,60l

In Denmark January 25, 1945 l 3 Claims. 1

A thunderstorm will often cause excess voltage on the telephone and telegraph overhead lines, which may, as known, result in extensive interruptions to the operation of the low voltage system and thereby increase the risk to life and property. Generally the damage to the systems consists of burnt-out fuses and relay coils, broken insulators, etc. Less frequently underground cables are damaged or bus bars broken.

The present invention serves the purpose of reducing these casualties, and experiments 'already made have proven that it is very well fitted for this purpose and even opens up the possibility of making the working of the systems for-all practical purposes independent of thunderstorms, apart from the very rare cases of direct strokes of lightning. i

It is known to use on electric high tension power plants certain fuses serving to protect overhead line masts against risks of fire and-insulators against being broken by excess voltage on the high tension power line. The protecting influence of these fuses is, however, greatly limited by various considerations, which include among other things, the fact that the power line is constantly under electric tension, which limits the reduction of the undesirable excess voltage.

According to the invention the undesirable excess voltages are grounded across a spark gap between the single line and the fastening support ing the line. The fastening is grounded in a known manner, e. g. through a guy, which may at the same time, serve as a stiffening for a number of cross bars which support the line. In the installation of new systems, this spark gap is produced by using and forming in a special manner the binding wire which is normally used for the attachment of the wire to the insulator supporting the line. The binding wire is wound around the line to one side of the insulator at a longer distance than necessary to keep the line in place, after which its free end is bent inwards towards the fastening and cut off at a proper distance from the fastening. On systems already existing, the spark gap is formed by winding a metal wire on the binding wire used and on the line itself, the end of the wire bein bent in a similar way as the above mentioned binding wire in new plants.

Such spark gaps are arranged at certain distances on the bars supporting the line, whereby it is rendered possible immediately to catch and ground the excess voltages practically at the very spot where they arise, so that they have no opportunity to propagate along the lines to the central stations and devices connected up with the plant.

In the drawing:

Figure 1 shows a conventional attachment of a low-voltage line to an insulator,

Fig. 2 shows an excess voltage cut-out according to the present invention, and

Figs. 3-6 show four diiferent constructional embodiments of the cut-out according to the present invention.

Fig. 1 shows how a low voltage line is generally attached to an insulator 3 by means of a binding wire 2, which is wound round the line as well as round the insulator. The latter is fastened with screws to the fastening 4 by means of the insulator pin l0, which is provided with a screw thread and two nuts. I 4..

,Fig. 2 shows a.simple constructional -embodi-. ment of. theexcess voltage cut-out accordinglto the present invention, the feature of. which. is that the binding wire 2 used for the attachment to the line I is made so long that it can be wound round the line at a longer distance than necessary to keep the line in place, and the free end 5 is then bent slantingly towards the fastening t, so that the distance between the fastening and the free end of wire 5 forms a spark gap 6, the fastening being in a known way connected with a ground wire. An excess of voltage passing along the line I will thereby seek the earth across for formed. spark gap 6.

In this way it is possible to reduce the excess voltages, which are very high during thunderstorms, to a small fraction of their original sizes, and as the output of an excess voltage is, as known, proportional to the square of the voltage, the importance of a reduction of the voltage will be recognised.

The sloping position of the end of wire 5 serves to facilitate the deviation of an excess of voltage coming from the right. Further, the end of wire 5 is attached free so as to prevent a possible deviation on the line I, formed by the deposit of dirt or snow and ice on the fastening and the insulator. The cut-out is attached at certain disstances on the line which is to be secured.

Fig. 3 shows another constructional embodiment of the cut-out. Over the binding wire 2 and the line I is wound a metal wire 1, the free end 8 of which is bent inwards towards the fastening 4, so that the spark gap 6 is now formed between this line and the fastening 4. This form of construction is tobe used on systems already existing with the result that the work in connection with the removal of the binding wire originally used is saved.

Fig. 4 shows a third constructional embodiment of the cut-out. In order to spare the fastening 4 against damage caused during the formation of sparks, a special piece of metal 9 is attached thereon together with the insulator 3, after which the spark gap 6 is formed between this piece of metal and the end of wire 5.

Fig. 5 shows a fourth constructional embodiw ment of the cut-out. In order to spare the wire I and the fastening 4 against damage caused during the formation of sparks, a specially shaped piece of metal H is attached to the fastening 4 together with the insulator 3', after which the spark gap 6 is formed between this piece ofrnetal and the extended binding wire 2..

Fig. 6 shows how the invention is used in r'espect to the leading in of the line wire I to a house. The insulator 3 is attached in a knownway to a special fastening l2 which is driven into the wall l3. The fastening I2 is grounded in the known way, after which the spark gap 6 is formed between the fastening and the end of wire 5'.

I claim:

1. An excess Voltage cut-out for low tension electric lines comprising a wire elementhelically wound about the line and binding said line to an insulator mounted on a grounded metal support, and a straight conductor extending at an acute angle tosaidline between the end of saidhelic'ally wound wire element and the grounded metal element, one end of said conductor being integral with one end of said hel'icall y' wound wire and the other end of said conductor being spaced from said grounded element to" form a spark gap;

2. An excess voltage cut o'ut for low tension electric unes comprising a wirefor bindin the line to an insulator, mounted on a grounded'meta-ii support; said wire being securedabout'the-insula tor and having at least one end helically wound about the line, and a straight conductor formed as a continuation" of said helically wound portion;

and extending from the end of said helically wound portion remote from the insulator at an acute angle to said line to a point spaced from the insulator support to form a spark gap between the free end of the straight conductor and said support.

3. Am excess voltage: cut-out for low tension electric lines comprising a wire for binding the line to an insulator, mounted on a grounded metal support, said wire being secured about the insulator and having at least one end helically wounda'bout the line, a spark gap electrode carried by said insulator support, and a straight condu'ctor formed as a continuation of said helically wound portion, and extending from the end of saidhelical'ly wound portion remote from the insulator' at an acute angle to said line to a point sp aced from the electrode carried by the insulator support to form a spark'gap between the free end of the straight conductor and said electrode.

KARL J QRGENSEN.

REFERENCES CITED:

Theronowing references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date" 262,210 Eck'ert' u--- Aug. 8, 1882 280,324; Noble a June 26,. 1883 991749 Rheinber'ger c May .9,- 1911 1,055-,322 DeLong We--- Mar. 11, 1913 1.116 303- Locke ee...... -o Nov: 3, 1914':

2,296,621. Wade du out-err Sept. 22,. 1 942 2,392,],342 Steinmayer Jan; 8, 1946 FOREIGN PATENTS- Number Country Date 371,357" England Apr. 19, 1932 

